1. Field of the Invention
This invention relates to novel N-heterocyclic compounds possessing a nitroso group on the heterocyclic N atom, which compounds are useful as intermediates in the preparation of photographic silver halide developing agents.
2. Description of the Prior Art
In recent years, there has been a growing interest in heterocyclic photographic developing agents, i.e., developers containing a heterocyclic ring as part of their structure. Some of these developing agents have the conventional hydroxyl or amino developing groups substituted on adjacent carbon atoms of a heterocyclic ring to provide structures similar to those of the developing agents in the aliphatic and aromatic series. Still other heterocyclic developing agents have one of the functional developing groups included as part of the heterocyclic ring. Copending U.S. patent application Ser. No. 721,859 of Stanley M. Bloom, which is a continuation-in-part of application Ser. No. 592,398 filed July 2, 1975, now abandoned, which, in turn, is a continuation-in-part of application Ser. No. 451,740 filed Mar. 18, 1974, now abandoned, discloses and claims the use of certain tricyclic developing agents of the latter type, i.e., developing agents having one of the functional developing groups included as part of a heterocyclic ring.
N-nitrosos compounds useful as intermediates in the synthesis of the aforementioned tricyclic developing agents comprise the subject matter of the present invention.